P-31 MR SPECTROSCOPY OF SKELETAL AND CARDIAC-MUSCLE METABOLISM IN PATIENTS WITH SYSTEMIC-SCLEROSIS - A MULTIPLE CASE-STUDY

Three-dimensionally localized proton-decoupled phosphorus-31 magnetic resonance (MR) spectroscopy of skeletal and cardiac muscle was perform ed in six patients with systemic sclerosis. Cardiac (n = 9) and skelet al (n = 6) spectra were also obtained in healthy volunteers. Metabolit e ratios and intracellular pH were determined from the spectra of skel etal and cardiac muscle. The phosphocreatine-to-adenosine triphosphate ratio was normal for both skeletal and cardiac muscle in patients wit h systemic sclerosis. The pH values of skeletal muscle were similar in patients and control subjects (7.13 +/- 0.02 vs 7.12 +/- 0.01, respec tively). In skeletal muscle, the inorganic phosphate-to-phosphocreatin e ratio in patients was increased relative to that of control subjects (0.106 +/- 0.014 vs 0.086 +/- 0.006, respectively; P = .02). P-31 MR spectroscopy showed no abnormalities in the myocardium of patients wit h systemic sclerosis. Assessment of the inorganic phosphate-to-phospho creatine ratio in peripheral skeletal muscle may be helpful for assess ing disease activity.